Despite getting hitched in a secret wedding just weeks ago, Naya Rivera is reportedly livid over her ex, Big Sean's new relationship with The Way singer Ariana Grande.

The 27-year-old Glee star just married Ryan Dorsey, 30, on July 19. But word is she always thought something was going on between her ex-fiancé and Grande, so news of them being a couple is reportedly her "worst nightmare."

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An insider told Hollywood Life Thursday, "Naya was trying to keep it together and have fun at the [Justin Timberlake] concert but she was really upset because of the news about Sean and Ariana. She kept bringing it up...She was always sure that Sean was cheating on her with Ariana, they fought a lot about that."

The source went on to say that the Clique rapper always denied any intimate relationship with Grande and went as far as referring to the 20-year-old as his little sister. Still, the bombshell actress is said to feel vindicated by speculation that Big Sean and Grande are together.

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"Naya feels like this is proof that she was right all along and Sean was hooking up with Ariana. She doesn't want him back, but it's still a huge wound and she's hurt and she's angry."

A separate insider confirmed that the two are indeed a couple earlier this week.

They told E! News Monday that they have been close to one another ever since they made the song Problem together. Rumors that they were dating started a fan saw them going into The Grove movie theater in Los Angeles for a late night showing of thriller The Purge. They were also said to be kissing during the entire movie.

Big Sean and Rivera called it quits back in January while Grande broke it off with her on-again-off-again boyfriend Jai Brooks in July.